1. Field of the Invention
The present invention relates to a radiographic image reading apparatus for reading radiographic image information stored in a storage phosphor sheet.
2. Description of Related Art
A radiographic image reading apparatus outputting image information as digital data has been frequently used for digitizing radiographic image information generated at hospitals to store and to telephotograph the digitized radiographic image information. As a radiographic image reading apparatus for outputting such digital data, a radiographic image reading apparatus using a storage phosphor sheet is well known.
In a radiographic image reading apparatus for reading the radiographic image information from the storage phosphor sheet as described above, a mechanism for taking out the storage phosphor sheet from the cassette and for conveying only the storage phosphor sheet in the apparatus, is ordinarily used. In such a conveyance mechanism, a one side reference conveying system in which the storage phosphor sheet is conveyed by shifting it to one side along the conveying direction thereof, is generally used. However, in a system in which the cassette is conveyed in the apparatus like the present invention, a conveying method in which the weight of the cassette is considered, is required. Further, because the weight difference between a small cassette having 18×24 cm size and a large cassette having 14″×17″ size is large, a technique that the both cassettes are stably conveyed and the image information is accurately read is required. On the other hand, in an operation in which the cassette is inserted into the apparatus, it is required that the information attached to the cassettes having various sizes is inexpensively and securely read. Further, a simple inserting method is required. As described above, in a system in which the cassette is conveyed in the apparatus, there are various problems to be solved as compared with a case in which only the storage phosphor sheet is conveyed in an apparatus.